Adaptation to new complete dentures-is the neuromuscular system outcome-oriented or effort-oriented?

OBJECTIVE: The aim of this study was to observe the adaptation strategy of the stomatognathic system during the adaptation of complete dentures, comprising masticatory parameters and subjective measures. Our hypothesis was that with new dentures, masticatory performance would increase while the effort of the system is kept constant. MATERIAL AND METHODS: Thirty-two patients received standardized new complete dentures. Masticatory performance tests were conducted with old dentures (T1), immediately after incorporation of new dentures (T2) and after an adaptation period of 3 months (T3). Patients habitually chewed the silicone-based artificial test food Optocal. The comminuted test food was analyzed and mean particle sizes (x50) were calculated. Simultaneously, surface EMGs of the anterior temporalis and masseter muscles were recorded. Specific (SMW) and total muscle work (TMW) were determined. Patients filled in the OHIP-49 questionnaire. Test conditions were compared using repeated-measures ANOVA with SPSS 22 (SPSS Inc.) RESULTS: Masticatory performance increased (P = 0.016) between old (x50 = 4.99 ± 0.28) and adapted new dentures (x50 = 4.80 ± 0.33). TMW deteriorated (P = 0.004) at T2 (from TMW1 = 119.77 ± 56.49 to TMW2 = 92.12 46.27), and increased again (P = 0.028) at T3 (TMW3 = 107.66 ± 44.65). OHIP scores decreased significantly in all subscales (P < 0.001…P = 0.046); the total score was reduced (P < 0.001) from 56.24 ± 29.05 (T1) to 34.66 ± 24.74 (T3). CONCLUSION: In complete denture wearers, masticatory performance improves over an adaptation period. Muscle work initially decreased before reaching its original level again after adaptation. Subjective parameters overestimated the functional improvements. CLINICAL SIGNIFICANCE: The subjective evaluation does not adequately reflect functional improvements. The assessment of function requires an adaptation period.

Undetected residual cement on standard or individualized all-ceramic abutments with cemented zirconia single crowns - a prospective randomized pilot trial.

OBJECTIVE: To assess the frequency and amount of residual cement after attachment of monolithic zirconia crowns to standard and individualized ceramic abutments. MATERIAL AND METHODS: Twenty patients (mean age 58.9 years at inclusion in the study; 30% male) were randomized to receive either a standard or an individualized abutment on a bone-level implant. Monolithic zirconia single crowns were attached to abutments by use of permanent glass-ionomer cement. Crowns were fabricated with an occlusal hole to enable unscrewing of the abutment-crown complex. Immediately after cementation, superstructures were removed and both the peri-implant soft tissue and the abutment-crown complex were photographed in a standardized manner, to detect residual cement. Photographs were analyzed using Corel Photo Paint X7, and residual cement-to-total abutment and residual cement-to-peri-implant soft tissue area ratios were calculated. RESULTS: Residual cement was observed for 9 of 10 (90%) individualized abutments, compared with 4 of 10 (40%) standard abutments (OR = 13.5, P = 0.049). Twenty-seven of 40 (68%) individualized abutment surfaces were affected, compared with 12 of 40 (30%) standard abutment surfaces. The probability of observing residual cement was approximately five times higher for the surfaces of individualized abutments than for those of standard abutments (P = 0.005). The mean amount of sulcus surface covered by cement was 1.17% (SD 2.85) for the individualized abutments and 3.78% (SD 7.40) for the standard abutments. The position of the margin significantly affected the amount of residual cement. CONCLUSION: Both individualized and standard all-ceramic abutments result in small amounts of subgingival residual cement on abutment and sulcus surfaces. However, use of individualized abutments does not guarantee complete avoidance of undetected cement rests. Undetected residual cement might be avoided by use of all-ceramic abutments with visible abutment shoulders.

Immediate Loading of Dental Implants in Edentulous Mandibles by Use of Locator® Attachments or Dolder® Bars: Two-Year Results from a Prospective Randomized Clinical Study.

PURPOSE: The study aims to evaluate survival and incidence of complications for pairs of implants placed in the front region of edentulous mandibles and immediately loaded with either bar or Locator attachments. MATERIALS AND METHODS: Forty-six patients with edentulous mandibles (mean age 69.4 years at inclusion in the study; 73.9% male) received two implants in the interforaminal area of the symphysis. Dolder bar or Locator attachments, allocated randomly, were then attached immediately, and both clips and a framework were fastened to the denture by the dental technician within 72 hours. RESULTS: During the first 3 months of the 2-year period of observation, eight implants in five patients were lost, and were removed. Survival was 89.1% and 93.5% for the bar and Locator groups, respectively. During the entire period of observation, 38 prosthetic complications required aftercare. Five dentures had to be removed or reworked after implant failure, but no superstructure was lost or had to be remade for prosthetic reasons. Survival of the original dentures was 93.5% and 95.7% for the bar and Locator groups, respectively. CONCLUSION: Within the limitations of this study, results from immediate loading of two implants in the edentulous mandible with either Locator or bar attachments hardly differed. Prosthetic complications and aftercare measures in the Locator group were frequent but easy to handle. Ease of repair and cleaning, in particular, might be reasons for choosing the single-attachment system.

Radiographic monitoring of changes in bone height after implant placement in combination with an internal sinus lift without graft material.

PURPOSE: The objective was to investigate changes in bone height after implant placement in combination with simultaneous internal sinus lift (ISL) without graft material. MATERIALS AND METHODS: For a retrospective clinical study, 101 implants placed in combination with ISL without graft were selected. The study included 66 patients (mean age 59.6 years) with radiographs from baseline (T0) and two follow-ups after mean times of 7 months (T1) and 17 months (T2). Apical changes in bone height were measured at the mesial and distal aspects of the implant. Correlation analysis was performed to identify factors affecting changes in bone height. RESULTS: Mean apical bone gains of 1.0 mm (mesial) and 1.7 mm (distal) were observed at T1. At T2, mean apical bone gains were 1.5 mm and 2.1 mm (distal). The change in apical bone height was significant between T0 and T1, between T0 and T2, and between T1 and T2. Rank correlation analysis revealed a significant correlation (Spearman rho: -0.2 to -0.4) between small initial bone height and a greater amount of apical bone gain. CONCLUSIONS: A gain in apical bone height can be expected if implants are placed in combination with ISL without graft material. Variability is high, however.

Immediate Loading of Two Dental Implants, in Edentulous Mandibles, with Locator® Attachments or Dolder® Bars: First Results from a Prospective Randomized Clinical Study.

OBJECTIVE: The study aims to evaluate survival and the incidence of complications for pairs of implants placed in the frontal area of edentulous mandibles and immediately loaded with either bar or Locator® (Zest Anchors LLC, Escondido, CA, USA) attachments. MATERIAL AND METHODS: Forty-six patients (mean age 69.4 years; 73.9% male) with edentulous mandibles each received two immediately loaded implants in the interforaminal area of the symphysis. Immediately after implant placement, Dolder® bar (Sub-Tec Wirobond; BEGO Implant Systems GmbH & Co. KG, Bremen, Germany) or Locator® attachments, allocated randomly, were attached, and both clips and a framework were incorporated into the denture by the dental technician. The implants were loaded within 72 hours. RESULTS: During a mean observation period of 6 months (maximum 24 months, SD 0.43) eight implants in five patients were lost. Survival was 93.5% for the Locator® group and 89.1% for the bar group. Estimated cumulative survival after 1 year of function was 93.4% for the Locator® group and 87.1% for the bar group. During the observation period, 12 prosthetic complications required aftercare. No superstructure was lost or had to be remade for prosthetic reasons, but five dentures had to be removed or reworked after implant failure. Survival of the original dentures was, therefore, 95.7% for the Locator® group and 93.5% for the bar group. CONCLUSION: Within the limitations of this study, immediate loading of two implants in the edentulous mandible with either Locator® or bar attachments did hardly differ. Ease of repair and cleaning, in particular, might be arguments for choosing the single attachment system.

Particle size distributions determined by optical scanning and by sieving in the assessment of masticatory performance of complete denture wearers.

OBJECTIVES: Standard procedure for the measurement of masticatory performance is the fractionated sieving of fragmented test food, which is substantially time consuming. The aim of this study was to introduce a less laborious, comparable, and valid technique based on scanning. METHODS: Fifty-six Optocal chewing samples were minced by wearers of complete dentures with 15 and 40 chewing strokes and analyzed by both a sieving and a scanning method. The sieving procedure was carried out using ten sieves (5.6, 4.0, 2.8, 2.0, 1.4, 1.0, 0.71, 0.5, 0.355, and 0.25 mm) and measuring the weight of the specific fractions. Scanning was performed with a flatbed scanner (Epson Expression1600Pro, Seiko Epson Corporation, Japan, 1,200 dpi). Scanned images underwent image analysis (ImageJ 1.42q, NIH, USA), which yielded descriptive parameters for each particle. Out of the 2D image, a volume was estimated for each particle. In order to receive a discrete particle size distribution, area-volume-conversion factors were determined. The cumulated weights yielded by either method were curve fitted with the Rosin-Rammler distribution (MATLAB, The MathWorks, Inc., Natick, USA) to determine the median particle size X 50. RESULTS: The Rosin-Rammler distributions for sieving and scanning resembled each other and showed an excellent correlation in 15/40 chewing strokes (r = 0.995/r = 0.971, P < 0.01, Pearson's correlation coefficient). The median particle sizes varied between 4.77/3.04 and 5.36/5.28 mm (mean 5.07/4.67) for scanning and 4.69/2.39 and 5.23/5.43 mm (mean 5.03/4.57) for sieving. On average, scanning overestimated the X 50 values by 1/2.4 %. The scanning method took 10 min per sample in contrast to 50 min for sieving. CONCLUSION: Optical scanning is a valid method comparable to sieving. CLINICAL RELEVANCE: The described method is feasible and appropriate for the measurement of masticatory performance of denture wearers.

Early loading of implants with fixed dental prostheses in edentulous mandibles: 7.2-year clinical results from a prospective study.

PURPOSE: The purpose of this prospective follow-up study was to evaluate survival and success of early-loaded implants placed in the edentulous mandible and the survival of the fixed dental prostheses (FDPs) after in mean 7.2 years. MATERIALS AND METHODS: Thirty-seven patients (mean age 64.5 years, 18.9% male) received 185 implants in the intraforaminal area of the edentulous mandible (five implants per patient). Within 2 weeks, all implants were early loaded with fixed dental prostheses. The patients were recalled once a year for clinical and radiographic examinations. The 17 patients (79 implants) attending the recall in 2012 were additionally asked for their satisfaction of functional and aesthetic aspects. RESULTS: During a mean observation time of 7.2 years, 20 implants were lost in 11 patients, resulting in implant survival of 89.2%. Eight of all implants (4.3%) had too much marginal bone loss to satisfy the criteria of success. A total of 19 prosthetic complications and aftercare measurements had to be performed between in mean 4.5 to 7.2 years of observation. The survival of the original FDPs decreased to 83.8%. Of the 17 patients attending the recall in 2012, a total 59.5% had a satisfactory oral hygiene. According to the criteria of Albrektsson, the success rate for the remaining 79 implants was 89.9% after in mean 11.7 years. Patient satisfaction for assessment of functional and aesthetic aspects was in median 9 and 8 on the numeric rating scales. CONCLUSION: Long-term observation of in mean 7.2 years showed satisfactory results for both implant and superstructure survival. Prosthetic complications were easy to repair in most cases, but patients' ability for oral hygiene was reduced after the longer observation period. Especially in elderly patients, their attitudes and manual skills should be considered when planning the design of a new superstructure.

Clinical performance of all-ceramic cantilever fixed dental prostheses: results of a 2-year randomized pilot study.

OBJECTIVE: To evaluate the clinical performance of zirconia-based cantilever fixed dental prostheses (FDPs). METHOD AND MATERIALS: Twenty-one cantilever FDPs with three or four units were designed to replace one premolar or incisor (no canines). The FDPs were divided into 11 zirconia cantilever FDPs (test group) and 10 metal-ceramic cantilever FDPs (control group) and randomly assigned to patients. The results documented included failures, complications, plaque accumulation, and esthetic performance. Statistical analysis was performed using the Mann-Whitney U and chi-square tests. RESULTS: During the 2-year observation period, a total of five clinically relevant complications in four patients occurred: three endodontic problems (two in the test group and one in the control group) and two veneer chippings (both in the test group). Plaque accumulation on the abutment teeth was not significantly different among groups. The esthetic performance of all FDPs was acceptable. CONCLUSION: Stability and esthetic performance were acceptable for all-ceramic cantilever FDPs fabricated with zirconia. A longer observation period and larger sample size are necessary to make valid predictions about the longevity of these restorations.

Influence of bone augmentation procedures on the short-term prognosis of simultaneously placed implants.

OBJECTIVES: The purpose of this study was to investigate the effect of simultaneous bone-augmentation procedures, and their combination, on the survival of dental implants and on the incidence of complications. MATERIAL AND METHODS: Within a retrospective analysis, 958 implants placed in 404 patients (mean age 58.18) were selected from a prospective clinical study. In 304 cases of reduced bone width, bone spreading (n = 217) with hand osteotomes, or bone splitting (n = 15), or guided bone regeneration (n = 72) combined with autogenous bone grafts were also performed. Eighty-eight implants were placed in combination with simultaneous internal sinus floor elevation without using graft material. For 194 additional implants, several augmentation procedures were combined because of extensive bone deficits. Three-hundred and seventy-two conventionally placed implants served as controls. Implant failures and complications were recorded after a mean observation period of 2.1 years (maximum 6.9 years). RESULTS: Seventeen failures and nine additional implant-related complications were observed. After 4 years, Kaplan-Meier curves revealed a probability of survival without complication of 97.5% for conventionally placed implants, and 95.8% for implants placed in combination with a single augmentation technique. If several augmentation techniques were combined, success decreased to 94.1%. Complication-free survival differences between combined augmentation techniques and conventionally placed implants were significant (P = 0.004). Age, gender, and location showed no effect on implant survival. CONCLUSIONS: It can be concluded that simultaneous bone-augmentation techniques slightly reduce short-term prognosis for dental implants. This effect was more pronounced when advanced defects required the combination of several augmentation procedures.

Differences in lightness, chroma, and hue in the anterior teeth of quinquagenarians and septuagenarians.

The purpose of this study was to evaluate, for both genders and two elderly age groups, differences in lightness, chroma, and hue of pairs of natural anterior teeth, so that more accurate information on color would be available for the production of dentures with a natural appearance. The subjects in the younger group (YG) were 54 to 56 years of age, those in the older group 73 to 75 (N = 195, 48% women). Tooth color was measured using a spectrophotometer. Mixed models were calculated for each pair of teeth, with gender as a fixed factor. Gender did not have a significant effect in either age group. In both groups, differences in chroma between upper canines and lateral incisors and in lightness and hue between upper and lower canines were observed. In the YG, additional differences were found, with the only exception of the comparison between upper central and lateral incisors. The nongender-specific color differences observed should be considered when producing denture teeth for these groups of patients, in order to come as close as possible to the natural color ideal.